STRUCTURE AND LOCATION OF MISFIT DISLOCATIONS IN INGAAS EPILAYERS GROWN ON VICINAL GAAS(001) SUBSTRATES

The atomic structure of misfit dislocations at In0.2Ga0.8As/GaAs interfaces misoriented 2-degrees-10-degrees from (001) has been investigated by high-resolution electron microscopy. The misfit dislocations are predominantly dissociated 60-degrees dislocations consisting of 90-degrees and 30-degrees Shockley partial dislocations and enclosed stacking faults. These dissociated 60-degrees dislocations form increasingly asymmetrically on the different {111} glide planes as the misorientation increases. The 90-degrees partial dislocations are not confined to the interface, but lie 0-100 angstrom beneath it. The 30-degrees partial dislocations, in turn, are pushed even further into the substrate.